Figure 5

Cochlear ganglion and nerve fibers. (A–C) Cresyl violet staining of midmodiolar methacrylate sections of the cochlear ganglion at the cochlear basal turn in Irs2^+/+Ptpn1^+/+ (A), Irs2^−/−Ptpn1^+/+ (B) and Irs2^−/−Ptpnr^−/−mice (C) at postnatal wk 11. A slight reduction in the cellular density was more evident in both mutants (B, C) compared with wild-type (A). (D–F) Myelin P0 immunostaining of the cochlear ganglion shows less intense labeling in Irs2^−/−Ptpn1^+/+ (E) and Irs2^−/−Ptpn1^−/− (F) mice than in control mice (D). (G–I) Accordingly, myelin P0 immunostaining of nerve fibers projecting from the cochlear ganglion to the sensory cells is less intense in Irs2^−/−Ptpn1^+/+ and Irs2^−/−Ptpn1^−/− (arrows in H and I) than in wild-type mice (G). (J–L) Similarly, a weaker neurofilament 200-kDa immunostaining is observed in Irs2^+/+Ptpn1^−/− (K, white arrow) and Irs2^−/−Ptpn1^−/− (L, white arrow) mice compared with wild-type mice (J). Scale bars: A–I, 50 µm; J–L, 75 µm.